A short fiber-reinforced rubber wherein a short fiber is formulated in order to provide strength or functionality (e.g. anisotropy, durability, etc.) to a rubber has been known. Properties of reinforced rubber very depending upon a kind, amount, orientation and dispersion state of the short fiber. Particularly, the improvement of properties such as strength, modulus, etc. are obtained, for example, by the improvement of the short fiber-rubber interactions (e.g. adhesion, bonding property, etc.). The improvement of short fiber-rubber interactions can be conducted, for example, by subjecting the short fiber to a surface treatment [e.g. resolcin-formalin-latex (RFL), etc.] or a surface modification (e.g. graft treatment, plasma treatment, etc.).
However, the surface treatment or surface modification of the short fiber is a complicated process in the production of the short fiber-reinforced rubber. In addition, it is generally costly and time consuming to develop a suitable surface treating agent or a surface modification method.